1. Field of the Invention
The present invention relates to a fastening bracket for attaching a deck cross member structuring a steering support frame to a vehicle body frame.
2. Description of the Related Art
A steering support frame is structured of a deck cross member bridged between right and left vehicle frames. The deck cross member is fixed with bolting fastening brackets attached to respective right and left ends thereof with respect to fitting parts of the vehicle frames. In this context, there is no problem when a fastening bracket is surface contacted with the corresponding fitting part without a gap or a deviation therebetween. However, a gap inevitably exists between the fastening bracket and the fitting part. Furthermore, a positional deviation between the fastening nut and a bolt hole is inevitable. There is a problem in that the fastening bracket is deformed and strength (mechanical strength) is lowered when the fastening bracket is bolted to the fitting part in such a condition. A gap between the fastening bracket and the fitting part can be eliminated by interposing a spacer therebetween. However, a problem occurs that the number of parts and the number of steps are increased. In order to solve such a problem, there have been proposed fastening brackets disclosed in Japanese Patent No. 3778762 and Japanese Patent Application Publication No. 2006-199050.
In Japanese Patent No. 3778762, a gap with a fitting part is adjusted by providing a relative difference in strength of fastening brackets (cylindrical flange parts) attached to right and left ends of a deck cross member (frame). Specifically, a fastening bracket having higher strength is surface contacted with a vehicle body frame (pillar) for bolting and a fastening bracket having lower strength is deformed when used for bolting to the vehicle body frame. A deformation anticipated part that is elastically deformed or plastically deformed is disclosed as means for providing the relative difference in strength of the fastening brackets. For example, a crossing groove (groove part 5a) and a crossing hole (long hole 5b) formed between a boss (boss part 6) and a fastening nut (nut 8) for connecting a deck cross member are disclosed as specific examples of the deformation anticipated part (see FIG. 8 and FIG. 9 of Japanese Patent No. 3778762).
In Japanese Patent Application Publication No. 2006-199050, a dimensional adjustment deforming section 20 is formed to surround a fastening nut (project nut 11) in a fastening bracket (attachment mechanism 10) to be attached to each of the right and left ends of a deck cross member (steering member 1). Accordingly, the dimensional adjustment deforming section 20 is deformed towered a vehicle body frame (vehicle body side) to eliminate a gap between the fastening bracket and a fitting part. The dimensional adjustment deforming section 20 is formed by disposing a long hole (slit 20a) to surround the vicinity of a fastening nut (described as the “projection bolt 8” in the specification although considered as a misdescription of the “projection nut 11”) (see FIG. 4 of Japanese Patent Application Publication No. 2006-199050).
The fastening bracket having the “deformation anticipated part” or “a dimensional adjustment deforming section” described in Japanese Patent No. 3778762 and Japanese Patent Application Publication No. 2006-199050 does not need to interpose a spacer, so that the number of parts and the number of steps can be reduced. However, when a positional deviation exists between the fastening nut and the bolt hole, the deformation anticipated part or the dimensional adjustment deforming section may be burred. This results in insufficient elastic deformation or plastic deformation of the deformation anticipated part or the dimensional adjustment deforming section, and makes it impossible to eliminate a gap between the fastening bracket and the fitting part. Furthermore, a bolt that is screwed into the fastening nut may be inclined. This may cause a male screw to strip a female screw of the fastening nut, resulting in a fastening torque loss. In addition, sufficient fastening intensity of the bolt may not be secured, resulting in loosening of the bolt due to vibration generated while traveling, for example.
An object of the present invention is to provide a fastening bracket capable of adjusting a gap between the fastening nut and the fitting part and a positional deviation between the fastening nut and the bolt hole by elastic deformation or plastic deformation of a part including the fastening nut.